Exploiting Mycosporines as Natural Molecular Sunscreens for the Fabrication of UV-Absorbing Green Materials

Decoding the photoprotection strategies and manipulating cyanobacterial photoprotective metabolites, mycosporine-like amino acids, for next-generation sunscreens

The most recent evaluation of the impacts of UV-B radiation and depletion of stratospheric ozone points out the need for effective photoprotection strategies for both biological and nonbiological components. To mitigate the disruptive consequences of artificial sunscreens, photoprotective compounds synthesized from gram-negative, oxygenic, and photoautotrophic prokaryote, cyanobacteria have been studied. In a quest to counteract the harmful UV radiation, cyanobacterial species biosynthesize photoprotective metabolites named as mycosporine-like amino acids (MAAs). The investigation of MAAs as potential substitutes for commercial sunscreen compounds is motivated by their inherent characteristics, such as antioxidative properties, water solubility, low molecular weight, and high molar extinction coefficients. These attributes contribute to the stability of MAAs and make them promising candidates for natural alternatives in sunscreen formulations. They are effective at reducing direct damage caused by UV radiation and do not lead to the production of reactive oxygen radicals. In order to better understand the role, ecology, and its application at a commercial scale, tools like genome mining, heterologous expression, and synthetic biology have been explored in this review to develop next-generation sunscreens. Utilizing tactical concepts of bio-nanoconjugate formation for the development of an efficient MAA-nanoparticle conjugate structure would not only give the sunscreen complex stability but would also serve as a promising tool for the production of analogues. This review would provide insight on efforts to produce MAAs by diversifying the biosynthetic pathways, modulating the precursors and stress conditions, and comprehending the gene cluster arrangement for MAA biosynthesis and its application in developing effective sunscreen.

Applications of mycosporine-like amino acids beyond photoprotection

Recent years have seen a lot of interest in mycosporine-like amino acids (MAAs) because of their alleged potential as a natural microbial sunscreen. Since chemical ultraviolet (UV) absorbers are unsafe for long-term usage, the demand for natural UV-absorbing substances has increased. In this situation, MAA is a strong contender for an eco-friendly UV protector. The capacity of MAAs to absorb light in the UV-A (320-400 nm) and UV-B (280-320 nm) range without generating free radicals is potentially relevant in photoprotection. The usage of MAAs for purposes other than photoprotection has now shifted in favor of medicinal applications. Aside from UV absorption, MAAs also have anti-oxidant, anti-inflammatory, wound-healing, anti-photoaging, cell proliferation stimulators, anti-cancer agents, and anti-adipogenic properties. Recently, MAAs application to combat SARS-CoV-2 infection was also investigated. In this review article, we highlight the biomedical applications of MAAs that go beyond photoprotection, which can help in utilizing the MAAs as promising bioactive compounds in both pharmaceutical and cosmetic applications.

Recent Advances and Future Prospects of Mycosporine-like Amino Acids

Mycosporine-like amino acids (MAAs) are a class of water-soluble active substances produced by various aquatic organisms. However, due to the limitations of low accumulation of MAAs in organisms, the cumbersome extraction process, difficult identification, and high cost, MAAs have not yet been widely used in human life. Recently, there has been an emergence of heterologous synthesis for MAAs, making increasing yield the key to the quantification and application of MAAs. This review summarizes the latest research progress of MAAs, including: (1) introducing the biodistribution of MAAs and the content differences among different species to provide a reference for the selection of research subjects; (2) elaborating the species and molecular information of MAAs; (3) dissecting the synthesis mechanism and sorting out the synthesis pathways of various MAAs; (4) summarizing the methods of extraction and identification, summarizing the advantages and disadvantages, and providing a reference for the optimization of extraction protocols; (5) examining the heterologous synthesis method; and (6) summarizing the physiological functions of MAAs. This paper comprehensively updates the latest research status of MAAs and the various problems that need to be addressed, especially emphasizing the potential advantages of heterologous synthesis in the future production of MAAs.

Isolation of Mycosporine-like Amino Acids from Red Macroalgae and a Marine Lichen by High-Performance Countercurrent Chromatography: A Strategy to Obtain Biological UV-Filters

Marine organisms have gained considerable biotechnological interest in recent years due to their wide variety of bioactive compounds with potential applications. Mycosporine-like amino acids (MAAs) are UV-absorbing secondary metabolites with antioxidant and photoprotective capacity, mainly found in organisms living under stress conditions (e.g., cyanobacteria, red algae, or lichens). In this work, five MAAs were isolated from two red macroalgae (Pyropia columbina and Gelidium corneum) and one marine lichen (Lichina pygmaea) by high-performance countercurrent chromatography (HPCCC). The selected biphasic solvent system consisted of ethanol, acetonitrile, saturated ammonium sulphate solution, and water (1:1:0.5:1; v:v:v:v). The HPCCC process for P. columbina and G. corneum consisted of eight separation cycles (1 g and 200 mg of extract per cycle, respectively), whereas three cycles were performed for of L. pygmaea (1.2 g extract per cycle). The separation process resulted in fractions enriched with palythine (2.3 mg), asterina-330 (3.3 mg), shinorine (14.8 mg), porphyra-334 (203.5 mg) and mycosporine-serinol (46.6 mg), which were subsequently desalted by using precipitation with methanol and permeation on a Sephadex G-10 column. Target molecules were identified by HPLC, MS, and NMR.

Extraction of Mycosporine-like Amino Acids and Proteins from the Agarophyte Gelidium corneum Using Pulsed Power Techniques

Gelidium corneum (syn. sesquipedale) is an industrially and ecologically important species of red alga used for the production of high-quality agar. However, the species is also of growing interest for the production of other valuable compounds, such as mycosporine-like amino acids (MAAs), with potential cosmeceutical and biomedical applications. Novel methods using two pulsed power techniques, high-voltage electrical discharges (HVED) and pulsed electrical fields (PEF), were evaluated for efficacy of MAA extraction. Algal suspensions were prepared at two ratios (1:20 and 1:40 w:v). Four different extraction protocols were compared: (i) high-voltage electrical discharges, (ii) pulsed electric fields, (iii) maceration at room temperature, and (iv) maceration at 50 °C. The algae were treated in three states: freshly harvested, dried, and powdered. HVED and PEF treatments were effective when performed on fresh algae, and in particular the HVED treatment resulted in yields of MAAs twenty times higher than the control: 0.81 ± 0.05 mg/g_{Dry Weight (DW)} vs. 0.037 ± 0.002 mg/g_DW. This effect was not observed to the same extent when the algae were dried or powdered, although HVED remained the most selective method overall.

Molecular mechanisms of Marine-Derived Natural Compounds as photoprotective strategies

Excessive exposure of the skin to ultraviolet radiation (UVR) causes oxidative stress, inflammation, immunosuppression, apoptosis, and changes in the extracellular matrix, which lead to the development of photoaging and photodamage of skin. At the molecular level, these pathological changes are mainly caused by the activation of related protein kinases and downstream transcription pathways, the increase of matrix metalloproteinase, the formation of reactive oxygen species, and the combined action of cytokines and inflammatory mediators. At present, the photostability, toxicity, and damage to marine ecosystems of most sun protection products in the market have affected their efficacy and safety. Another way is to use natural products produced by various marine species. Marine organisms have evolved a variety of molecular strategies to protect themselves from the harmful effects of ultraviolet radiation, and their unique chemicals have attracted more and more attention in the research of photoprotection and photoaging resistance. This article provides an extensive description of the recent literature on the potential of Marine-Derived Natural Compounds (MDNCs) as photoprotective and photoprotective agents. It reviews the positive effects of MDNCs in counteracting UV-induced oxidative stress, inflammation, DNA damage, apoptosis, immunosuppression, and extracellular matrix degradation. Some MDNCs have the potential to develop feasible solutions for related phenomena, such as photoaging and photodamage caused by UVR.

Synthesis of Novel Ultraviolet Absorbers and Preparation and Field Application of Anti-Ultraviolet Aging PBAT/UVA Films

Poly-(butylene adipate-co-terephthalate) (PBAT) has become one of the most prevalent biodegradable plastic film materials owing to its good degradability, mechanical properties, and processability. However, the degradation time of this material was too fast and the functional period was short, which limited its application. Herein, three new tropolone-based UV absorbers (UVA-1C, UVA-4C and UVA-6C) were rationally designed and blended into PBAT. The PBAT/UVA films that formed were used against UV aging and prolonged the functional period of PBAT film. The three new absorbers were synthesized by bridging two tropolones using three different organic chains with different flexibility. Among them, the UVA-6C showed the strongest UV absorbance at around 238 nm and 320 nm. Consequently, the PBAT/UVA-6C film showed an extended validity period of 240 h in the Xenon lamp aging machine and a prolonged functional period of 8 d during the field application test when compared to pure PBAT. More importantly, a 7.8% increase in the maize yield was obtained under PBAT/UVA-6C film relative to pure PBAT film. Obviously, the novel prepared UVA-6C compound is a good candidate for UV absorption in PBAT, which makes PBAT/UVA-6C film more advantageous over pure PBAT in practical applications as biodegradable agricultural film.

Characterization of Antioxidant Activity of Heated Mycosporine-like Amino Acids from Red Alga Dulse Palmaria palmata in Japan

We recently demonstrated the monthly variation and antioxidant activity of mycosporine-like amino acids (MAAs) from red alga dulse in Japan. The antioxidant activity of MAAs in acidic conditions was low compared to that in neutral and alkali conditions, but we found strong antioxidant activity from the heated crude MAA fraction in acidic conditions. In this study, we identified and characterized the key compounds involved in the antioxidant activity of this fraction. We first isolated two MAAs, palythine, and porphyra-334, from the fraction and evaluated the activities of the two MAAs when heated. MAAs possess absorption maxima at around 330 nm, while the heated MAAs lost this absorption. The heated MAAs showed a high ABTS radical scavenging activity at pH 5.8–8.0. We then determined the structure of heated palythine via ESI-MS and NMR analyses and speculated about the putative antioxidant mechanism. Finally, a suitable production condition of the heated compounds was determined at 120 °C for 30 min at pH 8.0. We revealed compounds from red algae with antioxidant activities at a wide range of pH values, and this information will be useful for the functional processing of food.

Coral holobionts and biotechnology: from Blue Economy to coral reef conservation

Corals are of ecological and economic importance, providing habitat for species and contributing to coastal protection, fisheries, and tourism. Their biotechnological potential is also increasingly recognized. Particularly, the production of pharmaceutically interesting compounds by corals and their microbial associates stimulated natural product-based drug discovery. The efficient light distribution by coral skeletons for optimal photosynthesis by algal symbionts has led to 3D-printed bionic corals that may be used to upscale micro-algal cultivation for bioenergy generation. However, corals are under threat from climate change and pollution, and biotechnological approaches to increase their resilience, like 'probiotics' and 'assisted evolution', are being evaluated. In this review, we summarize the recent biotechnological developments related to corals with an emphasis on coral conservation, drug discovery and bioenergy.

Microalgae as a Source of Mycosporine-like Amino Acids (MAAs); Advances and Future Prospects

Mycosporine-like amino acids (MAAs), are secondary metabolites, first reported in 1960 and found to be associated with the light-stimulated sporulation in terrestrial fungi. MAAs are nitrogenous, low molecular weight, water soluble compounds, which are highly stable with cyclohexenone or cycloheximine rings to store the free radicals. Microalgae are considered as a good source of different kinds of MAAs, which in turn, has its own applications in various industries due to its UV absorbing, anti-oxidant and therapeutic properties. Microalgae can be easily cultivated and requires a very short generation time, which makes them environment friendly source of biomolecules such as mycosporine-like amino acids. Modifying the cultural conditions along withmanipulation of genes associated with mycosporine-like amino acids biosynthesis can help to enhance MAAs synthesis and, in turn, can make microalgae suitable bio-refinery for large scale MAAs production. This review focuses on properties and therapeutic applications of mycosporine like amino acids derived from microalgae. Further attention is drawn on various culture and genetic engineering approaches to enhance the MAAs production in microalgae.

Valorization of the Red Algae Gelidium sesquipedale by Extracting a Broad Spectrum of Minor Compounds Using Green Approaches

Until now, the red algae Gelidium sesquipedale has been primarily exploited for agar production, leaving an undervalued biomass. In this work, the use of eco-friendly approaches employing ultrasound-assisted extraction (UAE) and green solvents was investigated to valorize the algal minor compounds. The green methods used herein showed an attractive alternative to efficiently extract a broad spectrum of bioactive compounds in short extraction times (15 to 30 min vs. 8 h of the conventional method). Using the best UAE conditions, red seaweed extracts were characterized in terms of total phenolics (189.3 ± 11.7 mg GAE/100 g dw), flavonoids (310.7 ± 9.7 mg QE/100 g dw), mycosporine-like amino acids (MAAs) (Σ MAAs = 1271 mg/100 g dw), and phycobiliproteins (72.4 ± 0.5 mg/100 g dw). Additionally, produced algal extracts exhibited interesting antioxidant and anti-enzymatic activities for potential applications in medical and/or cosmetic products. Thus, this study provides the basis to reach a superior valorization of algal biomass by using alternative methods to extract biologically active compounds following eco-friendly approaches. Moreover, the strategies developed not only open new possibilities for the commercial use of Gelidium sesquipedale, but also for the valorization of different algae species since the techniques established can be easily adapted.

Protective effects of mycosporine-like amino acid-containing emulsions on UV-treated mouse ear tissue from the viewpoints of antioxidation and antiglycation

Mycosporine-like amino acids (MAAs) are promising natural antioxidative compounds with cosmetic applications for the prevention of skin aging. In this study, we evaluated the protective effects of natural resources-derived MAA-containing emulsions on mouse ear tissue exposed to UV irradiation. DBA/2CrSlc male mice were irradiated by UV light at 120 mJ/cm²/day for 9 days. MAA-containing emulsions were prepared using mycosporine-2-glycine (M2G), shinorine (SHI), or porphyra-334 (P334) and applied to mice ears at a dose of 50 mg/ear/day. After that, collected ear skin tissues were subjected to the observation of melanocytes, investigation for antioxidative stress markers, and measurement of advanced glycation-end products (AGEs). In addition, the antiglycative effects of MAAs were investigated in vitro. MAA-containing emulsions prepared in this study upregulated the activities of total superoxide dismutase (SOD) and catalase (CAT) in mouse ear tissue exposed to UV irradiation. Increased accumulation of copper/zinc (Cu/Zn) -SOD and/or CAT was also found in mouse ear tissue on which M2G- or P334-containing emulsion had been applied. Furthermore, P334 exhibited an antiglycative effect on elastin in vitro. Although MAA-containing emulsions have antioxidative effects as well as in vitro antiglycation, a protective effect by the accumulation of AGEs in mice ears exposed to UV was not observed. Thus, application of MAA-containing emulsions stimulated or protected the expression of antioxidant-associated proteins, thereby leading to upregulation of antioxidative activities in mouse ear skin samples tissues under UV irradiation. Additional optimization of MAA-containing emulsions, including composition, process, and dosage should be considered for further improvement of efficacy.

Exploring Mycosporine-Like Amino Acids (MAAs) as Safe and Natural Protective Agents against UV-Induced Skin Damage

Prolonged exposure to harmful ultraviolet radiation (UVR) can induce many chronic or acute skin disorders in humans. To protect themselves, many people have started to apply cosmetic products containing UV-screening chemicals alone or together with physical sunblocks, mainly based on titanium–dioxide (TiO₂) or zinc-oxide (ZnO₂). However, it has now been shown that the use of chemical and physical sunblocks is not safe for long-term application, so searches for the novel, natural UV-screening compounds derived from plants or bacteria are gaining attention. Certain photosynthetic organisms such as algae and cyanobacteria have evolved to cope with exposure to UVR by producing mycosporine-like amino acids (MAAs). These are promising substitutes for chemical sunscreens containing commercially available sunblock filters. The use of biopolymers such as chitosan for joining MAAs together or with MAA-Np (nanoparticles) conjugates will provide stability to MAAs similar to the mixing of chemical and physical sunscreens. This review critically describes UV-induced skin damage, problems associated with the use of chemical and physical sunscreens, cyanobacteria as a source of MAAs, the abundance of MAAs and their biotechnological applications. We also narrate the effectiveness and application of MAAs and MAA conjugates on skin cell lines.

Mycosporine-Like Amino Acids (MAAs): Biology, Chemistry and Identification Features

Mycosporines and mycosporine-like amino acids are ultra-violet-absorbing compounds produced by several organisms such as lichens, fungi, algae and cyanobacteria, especially upon exposure to solar ultraviolet radiation. These compounds have photoprotective and antioxidant functions. Mycosporine-like amino acids have been used as a natural bioactive ingredient in cosmetic products. Several reviews have already been developed on these photoprotective compounds, but they focus on specific features. Herein, an extremely complete database on mycosporines and mycosporine-like amino acids, covering the whole class of these natural sunscreen compounds known to date, is presented. Currently, this database has 74 compounds and provides information about the chemistry, absorption maxima, protonated mass, fragments and molecular structure of these UV-absorbing compounds as well as their presence in organisms. This platform completes the previous reviews and is available online for free and in the public domain. This database is a useful tool for natural product data mining, dereplication studies, research working in the field of UV-absorbing compounds mycosporines and being integrated in mass spectrometry library software.

Mycosporine-Like Amino Acids from Marine Resource

In the last 10 years, a great number of publications (both regular papers and reviews) have been published on the interesting molecules—mycosporine-like amino acids (MAAs). Despite significant advances in the research of MAAs, current overviews in the recent publications involving MAA research still need reporting. The aim of this Special Issue is to join, as an interdisciplinary approach, the photochemical and photobiological aspects, with emphasis on new natural resources to obtain both algae and zooplankton MAAs, advances in methodology of extraction and chemical identification of new MAAs. Finally, this Special Issue reviews the bioactivities of MAAs including UVR screen, antioxidant, immunostimulant, growth factor, DNA protection, inhibition of collagenase, elastase and hyaluronidase, and anti-photoaging, among others, and their potential use as nutracosmeceutic molecules (i.e., oral and topic photoprotector).

Robust natural ultraviolet filters from marine ecosystems for the formulation of environmental friendlier bio-sunscreens

Ultraviolet radiation (UVR) has detrimental effects on human health. It induces oxidative stress, deregulates signaling mechanisms, and produces DNA mutations, factors that ultimately can lead to the development of skin cancer. Therefore, reducing exposure to UVR is of major importance. Among available measures to diminish exposure is the use of sunscreens. However, recent studies indicate that several of the currently used filters have adverse effects on marine ecosystems and human health. This situation leads to the search for new photoprotective compounds that, apart from offering protection, are environmentally friendly. The answer may lie in the same marine ecosystems since molecules such as mycosporine-like amino acids (MAAs) and scytonemin can serve as the defense system of some marine organisms against UVR. This review will discuss the harmful effects of UVR and the mechanisms that microalgae have developed to cope with it. Then it will focus on the biological distribution, characteristics, extraction, and purification methods of MAAs and scytonemin molecules to finally assess its potential as new filters for sunscreen formulation.

Unplanned absorption of sunscreen ingredients: Impact of formulation and evaluation methods

Permeation of sunscreens agents reduces its effectiveness and safety, leading to systemic circulation and causing unknown adverse effects. In order to maintain the sunscreen efficacy and safety, the filters must stay on the skin surface, with minimum penetration through dermis. Even facing the possibility of filters permeation, the use of sunscreen is important to avoid skin damage as erythema, free-radicals formation, skin ageing and skin cancer, caused by ultraviolet radiation. Aiming potential side effects caused by topical absorption of sunscreens, studies are carried to improve formulation characteristics and stability, reduce skin permeation and evaluate sun protections factor (SPF). Current assays to detect the permeation of sunscreens involve in vivo or in vitro studies, to simulate physiological conditions of use. The aim of this review is to revisit sunscreen skin permeation data over the last decade and the factors that can enhance skin permeation or improve the sunscreen efficacy.

Antibacterial Multi-Layered Nanocellulose-Based Patches Loaded with Dexpanthenol for Wound Healing Applications

Antibacterial multi-layered patches composed of an oxidized bacterial cellulose (OBC) membrane loaded with dexpanthenol (DEX) and coated with several chitosan (CH) and alginate (ALG) layers were fabricated by spin-assisted layer-by-layer (LbL) assembly. Four patches with a distinct number of layers (5, 11, 17, and 21) were prepared. These nanostructured multi-layered patches reveal a thermal stability up to 200 °C, high mechanical performance (Young's modulus ≥ 4 GPa), and good moisture-uptake capacity (240-250%). Moreover, they inhibited the growth of the skin pathogen Staphylococcus aureus (3.2-log CFU mL-1 reduction) and were non-cytotoxic to human keratinocytes (HaCaT cells). The in vitro release profile of DEX was prolonged with the increasing number of layers, and the time-dependent data imply a diffusion/swelling-controlled drug release mechanism. In addition, the in vitro wound healing assay demonstrated a good cell migration capacity, headed to a complete gap closure after 24 h. These results certify the potential of these multi-layered polysaccharides-based patches toward their application in wound healing.

Untargeted Analysis for Mycosporines and Mycosporine-Like Amino Acids by Hydrophilic Interaction Liquid Chromatography (HILIC)-Electrospray Orbitrap MS2/MS3

Mycosporines and mycosporine-like amino acids have been described as natural sunscreens and antioxidant compounds presenting a great potential for health and cosmetic applications. Herein, an untargeted screening approach for mycosporines and mycosporine-like amino acids (MAAs) was developed by the coupling of zwitterionic hydrophilic interaction liquid chromatography (HILIC) with multistage electrospray mass spectrometry MS²/MS³ using an Orbitrap analyzer and fragment ion search (FISh). This method was applied to study the mycosporine and MAA contents of five algae extracted using a 50% methanol solution and sonication. Candidate-MAAs were detected by mining eight characteristic fragment ions in their HILIC data-dependent MS² mass spectrum. Their exact masses were measured with 3 ppm mass accuracy and their structures were elucidated on the basis of the MS³/MS⁴ mass spectra. The method developed was validated with a targeted analysis using an extract of Gymnogongrus devoniensis which confirmed the detection of 14 MAAs reported in the literature. In addition, 23 previously unreported MAAs were detected and the structures could be assigned for seven of them. The developed method was applied to the analysis of four algae: Gelidium sesquipedale, Halopithys incurva, Porphyra rosengurtii and Cystoseira tamariscifolia allowing the detection of MAAs, including some reported here for the first time.

Multifunctional nanofibrous patches composed of nanocellulose and lysozyme nanofibers for cutaneous wound healing

Cutaneous wounds frequently require the use of patches to promote healing, nevertheless, most commercial products are fabricated with non-biodegradable synthetic substrates that pose environmental problems upon disposal. Herein, the partnership between two biobased nanofibrous polymers, namely a polysaccharide (nanofibrillated cellulose (NFC)) and a protein (lysozyme nanofibers (LNFs)), is explored to design sustainable fibrous patches with good mechanical performance and biological functionalities for wound healing applications. Two patches with different morphologies were prepared by vacuum filtration of a water-based suspension of both nanofibers and by sequential filtration of the separated suspensions (layered patch). The resultant freestanding patches exhibited high thermal stability (up to 250 °C), mechanical performance (Young's modulus ≥3.7 GPa), and UV-barrier properties. The combination of the bioactive LNFs with the mechanically robust NFC conveyed antioxidant activity (76-79% DPPH scavenging) and antimicrobial activity against Staphylococcus aureus (3.5-log CFU mL^-1 reduction), which is a major benefit to prevent microbial wound infections. Moreover, these patches are biocompatible towards L929 fibroblast cells, and the in vitro wound healing assay evidenced a good migration capacity leading to an almost complete wound occlusion. Therefore, the partnership between the two naturally derived nanofibrous polymers represents a potential blueprint to engineer sustainable multifunctional patches for cutaneous wound healing.

Efficient Extraction and Antioxidant Capacity of Mycosporine-Like Amino Acids from Red Alga Dulse Palmaria palmata in Japan

Mycosporine-like amino acids (MAAs) are the ultraviolet (UV)-absorbable compounds, which are naturally produced by cyanobacteria and algae. Not only these algae but also marine organisms utilize MAAs to protect their DNA from UV-induced damage. On the other hand, the content of MAAs in algae was changed by the environmental condition and season. In addition to the UV-protected function, the antioxidant capacity of MAAs can apply to the cosmetic sunscreen materials and anti-cancer for human health. In this study, we developed the efficient extraction method of MAAs from red alga dulse in Usujiri (Hokkaido, Japan) and investigated the monthly variation. We also evaluated the antioxidant capacity. We employed the successive extraction method of water and then methanol extraction. Spectrophotometric and HPLC analyses revealed that the yield of MAAs by 6 h water extraction was the highest among the tested conditions, and the content of MAAs in the sample of February was the most (6.930 µmol g-1 dry weight) among the sample from January to May in 2019. Antioxidant capacity of MAAs such as crude MAAs, the purified palythine and porphyra-334 were determined by 2,2'-azinobis(3-ethylbenzothiazoline 6-sulfonic acid) (ABTS) radical scavenging and ferrous reducing power assays in various pH conditions, showing that the highest scavenging activity and reducing power were found at alkaline condition (pH 8.0).

Films of chitosan and natural modified hydroxyapatite as effective UV-protecting, biocompatible and antibacterial wound dressings

Chitosan is a natural polysaccharide widely used in biomedicine, for instance for wound dressing. Hydroxyapatite is a very bioactive calcium phosphate which, if modified with an appropriate element (iron Fe), can also have UV-absorbing properties. In this work, we report the study of films of chitosan incorporated with iron-modified hydroxyapatite of natural origin (from cod fish bones); this combination led to an innovative chitosan-based material with excellent and advanced functional properties. The films showed very high UV absorption (Ultraviolet Protection Factor (UPF) value higher than 50). This is the first time that a chitosan-based material has shown such high UV protection properties. The films also showed to be non-cytotoxic, and possessed antimicrobial activity towards both Gram-positive and negative strains. Their mechanical properties, optimised with an experimental design approach, confirmed their potential use as multifunctional wound dressing, capable of reducing bacterial infections and, at the same time, protecting from UV light.

Marine-Derived Polymeric Materials and Biomimetics: An Overview

The review covers recent literature on the ocean as both a source of biotechnological tools and as a source of bio-inspired materials. The emphasis is on marine biomacromolecules namely hyaluronic acid, chitin and chitosan, peptides, collagen, enzymes, polysaccharides from algae, and secondary metabolites like mycosporines. Their specific biological, physicochemical and structural properties together with relevant applications in biocomposite materials have been included. Additionally, it refers to the marine organisms as source of inspiration for the design and development of sustainable and functional (bio)materials. Marine biological functions that mimic reef fish mucus, marine adhesives and structural colouration are explained.

Bioinspired biomolecules: Mycosporine-like amino acids and scytonemin from Lyngbya sp. with UV-protection potentialities

Since the beginning of life on Earth, cyanobacteria have been exposed to natural ultraviolet-A radiation (UV-A, 315-400 nm) and ultraviolet-B radiation (UV-B, 280-315 nm), affecting their cells' biomolecules. These photoautotrophic organisms have needed to evolve to survive and thus, have developed different mechanisms against ultraviolet radiation. These mechanisms include UVR avoidance, DNA repair, and cell protection by producing photoprotective compounds like Scytonemin, carotenoids, and Mycosporine-like amino acids (MAAs). Lyngbya marine species are commercially important due to their secondary metabolites that show a range of biological activities including antibacterial, insecticidal, anticancer, antifungal, and enzyme inhibitor. The main topic in this review covers the Lyngbya sp., a cyanobacteria genus that presents photoprotection provided by the UV-absorbing/screening compounds such as MAAs and Scytonemin. These compounds have considerable potentialities to be used in the cosmeceutical, pharmaceutical, biotechnological and biomedical sectors and other related manufacturing industries with an additional value of environment friendly in nature. Scytonemin has UV protectant, anti-inflammatory, anti-proliferative, and antioxidant activity. MAAs act as sunscreens, provide additional protection as antioxidants, can be used as UV protectors, activators of cell proliferation, skin-care products, and even as photo-stabilizing additives in paints, plastics, and varnishes. The five MAAs identified so far in Lyngbya sp. are Asterina-330, M-312, Palythine, Porphyra-334, and Shinorine are capable of dissipating absorbed radiation as harmless heat without producing reactive oxygen species.

Mycosporine-Like Amino Acids for Skin Photoprotection

BACKGROUND

Excessive human exposure to solar ultraviolet radiation (UVR) continues to be a major public health concern, with skin cancer rates increasing year on year. The major protective measure is the use of synthetic UVR filters formulated into sunscreens, but there is a growing concern that some of these chemicals cause damage to delicate marine ecosystems. One alternative is the use of biocompatible mycosporine-like amino acids (MAA), which occur naturally in a wide range of marine species. Their role within nature is mainly thought to be photoprotective. However, their potential for human photoprotection is largely understudied.

OBJECTIVE

To review the role of MAA in nature and assess their potential as natural sunscreens for human skin photoprotection.

METHOD

A literature review of all relevant papers was conducted.

CONCLUSION

MAA are natural photostable compounds that are thought to offer photoprotection to marine species. Initially thought of as protective based on their absorption properties in the solar UVR spectrum, it is clear that MAA are multifunctional photoprotective compounds acting as chemical and biological anti-oxidants. This suggests that MAA may offer a novel eco-friendly approach to human skin photoprotection. Most studies have been carried out in vitro and current data strongly suggest that MAA have potential for development as natural biocompatible sunscreens that protect against a diverse range of solar UVR induced adverse effects on human health.

Mycosporine-Like Amino Acids (MAAs) in Time-Series of Lichen Specimens from Natural History Collections

Mycosporine-like amino acids (MAAs) were quantified in fresh and preserved material of the chlorolichen Dermatocarpon luridum var. luridum (Verrucariaceae/Ascomycota). The analyzed samples represented a time-series of over 150 years. An HPLC coupled with a diode array detector (HPLC-DAD) in hydrophilic interaction liquid chromatography (HILIC) mode method was developed and validated for the quantitative determination of MAAs. We found evidence for substance specific differences in the quality of preservation of two MAAs (mycosporine glutamicol, mycosporine glutaminol) in Natural History Collections. We found no change in average mycosporine glutamicol concentrations over time. Mycosporine glutaminol concentrations instead decreased rapidly with no trace of this substance detectable in collections older than nine years. Our data predict that a screening for MAAs in organism samples from Natural History Collections can deliver results that are comparable to those obtained from fresh collections only for some MAAs (e.g., mycosporine glutamicol). For other MAAs, misleading, biased, or even false negative results will occur as a result of the storage sensitivity of substances such as mycosporine glutaminol. Our study demonstrates the value of pilot studies with time-series based on model taxa with a rich representation in the Natural History Collections.

UV Photoprotection, Cytotoxicity and Immunology Capacity of Red Algae Extracts

This study was designed to evaluate the potential use of algal extracts in cosmeceuticals, including factors related to biosecurity. The aqueous crude extracts of Hydropuntia cornea and Gracilariopsis longissima showed a good photoprotective capacity (Sun Protection Factor, SPF) due to, among other reasons, the presence of five types of mycosporine-like amino acids (MAAs) detected by high pressure liquid chromatography-photodiode array detector (HPLC-PDA) and electrospray ionization mass spectrometry (ESI-MS) (Palythine, Asterina-330, Shinorine, Porphyra-334, and Palythinol). The toxicity of the extracts was evaluated by the MTT assay, which is based on the metabolic reduction of MTT [3-(4,5-dimethylthiazol-2yl)-diphenyl tetrazolium bromide] by the action of the mitochondrial enzyme succinate dehydrogenase. This assay was carried out in vitro in three cell lines: one related to the immune system (murine macrophages of the immune system: RAW264.7) and two human cell lines related to the skin (gingival fibroblasts: HGF, and immortalized human keratinocytes: HaCaT). Both extracts showed no cytotoxic activity in both types of human cells, whereas they showed cytotoxicity in murine tumor cells of the immune system (macrophages: RAW264.7). On the other hand, the immunological activity in the murine macrophage RAW264.7 was studied at a concentration lower than 100 μg mL^-1 and lower than the EC₅₀, and evaluated by the production of pro-inflammatory compounds through an immunosorbent assay linked to enzymes such as tumor necrosis factor-α (TNF-α) or anti-inflammatory/proinflammatory enzymes such as interleukin-6 (IL-6). Both algae extracts induced the biosynthesis of TNF-α and IL-6. The production of TNF-α was much higher than that observed in the control (at a concentration of the aqueous extract higher than 5 μg mL^-1). These results support the theory that the extracts of H. cornea and G. longissima actively induce the production of cytokines. In summary, the extracts of these species did not show cytotoxicity in human cells, and they present with immunomodulatory and photoprotection capacity.

UVA and UVB Photoprotective Capabilities of Topical Formulations Containing Mycosporine-like Amino Acids (MAAs) through Different Biological Effective Protection Factors (BEPFs)

The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5–8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.

Cosmetics and Cosmeceutical Applications of Chitin, Chitosan and Their Derivatives

Marine resources are well recognized for their biologically active substances with great potential applications in the cosmeceutical industry. Among the different compounds with a marine origin, chitin and its deacetylated derivative—chitosan—are of great interest to the cosmeceutical industry due to their unique biological and technological properties. In this review, we explore the different functional roles of chitosan as a skin care and hair care ingredient, as an oral hygiene agent and as a carrier for active compounds, among others. The importance of the physico-chemical properties of the polymer in its use in cosmetics are particularly highlighted. Moreover, we analyse the market perspectives of this polymer and the presence in the market of chitosan-based products.

Photochemistry and Photophysics of Shinorine Dimethyl Ester

The photostability and photophysical properties of the dimethyl ester of the mycosporine-like amino acid shinorine have been experimentally evaluated in aqueous solution and in the presence of direct micelles prepared with a cationic or an anionic detergent, respectively. In comparison with shinorine, the ester molecule increases the photostability, the fluorescence quantum yield and the fluorescence lifetime in water as well as in the micellar solutions. The effects are more pronounced in sodium dodecyl sulfate solutions and suggest that the electrostatic attractions with the micellar interface contribute to limit the movement of the molecules and influence the relative rate of their deactivation channels. However, the predominance of the nonradiative decay is maintained together with the UV photoprotective ability of this atypical mycosporine species.

Mycosporine-Like Amino Acids: Potential Health and Beauty Ingredients

Human skin is constantly exposed to damaging ultraviolet radiation (UVR), which induces a number of acute and chronic disorders. To reduce the risk of UV-induced skin injury, people apply an additional external protection in the form of cosmetic products containing sunscreens. Nowadays, because of the use of some chemical filters raises a lot of controversies, research focuses on exploring novel, fully safe and highly efficient natural UV-absorbing compounds that could be used as active ingredients in sun care products. A promising alternative is the application of multifunctional mycosporine-like amino acids (MAAs), which can effectively compete with commercially available filters. Here, we outline a complete characterization of these compounds and discuss their enormous biotechnological potential with special emphasis on their use as sunscreens, activators of cells proliferation, anti-cancer agents, anti-photoaging molecules, stimulators of skin renewal, and functional ingredients of UV-protective biomaterials.

Photophysicochemical characterization of mycosporine-like amino acids in micellar solutions

The properties and photochemical and photophysical behavior of the mycosporine-like amino acids (MAAs) shinorine and porphyra-334 were experimentally evaluated in solutions of direct ionic micelles as simple biomimicking environments. The preferential partition of the natural molecules in the aqueous phase of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC) micellar systems is confirmed. Although the proton dissociation of the carboxylic groups in the MAAs is slightly inhibited in CTAC solutions, the molecules are predicted to be in the form of zwitterions in all the explored media around physiological pH. The increase in the fluorescence quantum yield, emission lifetime and stationary anisotropy in the presence of CTAC micelles suggest electrostatic attractions of the MAAs with the surface of the cationic micelles. Consistently, the triplet-triplet absorption spectra in CTAC solutions reveal the typical environmental features of the micellar interface, while in the presence of SDS they are similar to those determined in neat water. Finally, the photostability of the MAAs increases in the micellar systems, more noticeably in the case of CTAC. It is concluded that the ability of the two MAAs to act as UV screens is susceptible to the influence of electrostatic interactions with organized microheterogeneous environments.

Immunomodulatory Effects of the Mycosporine-Like Amino Acids Shinorine and Porphyra-334

Mycosporine-like amino acids (MAAs) are secondary metabolites, produced by a large variety of microorganisms including algae, cyanobacteria, lichen and fungi. MAAs act as UV-absorbers and photo-protectants. MAAs are suggested to exert pharmaceutical relevant bioactivities in the human system. We particularly focused on their effect on defence and regulatory pathways that are active in inflamed environments. The MAAs shinorine and porphyra-334 were isolated and purified from the red algae Porphyra sp. using chromatographic methods. The effect of MAAs on central signaling cascades, such as transcription factor nuclear factor kappa b (NF-κB) activation, as well as tryptophan metabolism, was investigated in human myelomonocytic THP-1 and THP-1-Blue cells. Cells were exposed to the MAAs in the presence or absence of lipopolysaccharide (LPS). NF-κB activity and the activity of tryptophan degrading enzyme indoleamine 2,3-dioxygenase (IDO-1) were used as readout. Compounds were tested in the concentration range from 12.5 to 200 µg/mL. Both MAAs were able to induce NF-κB activity in unstimulated THP-1-Blue cells, whereby the increase was dose-dependent and more pronounced with shinorine treatment. While shinorine also slightly superinduced NF-κB in LPS-stimulated cells, porphyra-334 reduced NF-κB activity in this inflammatory background. Modulation of tryptophan metabolism was moderate, suppressive in stimulated cells with the lower treatment concentration of both MAAs and with the unstimulated cells upon porphyra-334 treatment. Inflammatory pathways are affected by MAAs, but despite the structural similarity, diverse effects were observed.

Plant-based active photoprotectants for sunscreens

Excessive exposure to the sun's radiation is the major exogenous mediator of skin damage, which accelerates skin ageing and increases the risk of developing skin cancer. Compounds with photoprotectant activity are extremely useful for decreasing the effect of ultraviolet (UV) radiation on the skin; however, numerous sun filters, especially organic sunscreens, are allergenic. Therefore, the development of formulations containing plant extracts, which may be potentially safer, is extensively being explored. Plant-based cosmetics are commonly used to avoid skin ageing because they contain antioxidant agents that minimize free radical activity, and numerous studies have investigated the skin-protectant effects of related plant species. In addition to their antioxidant properties, plant-based cosmetics protect the skin against solar radiation because they contain polyphenols such as flavonoids and carotenoids. Therefore, this study aims to present a review of plant species commonly used in sunscreens to protect the skin against damage due to sunlight exposure.

Xanthones of Lichen Source: A 2016 Update

An update of xanthones encountered in lichens is proposed as more than 20 new xanthones have been described since the publication of the compendium of lichen metabolites by Huneck and Yoshimura in 1996. The last decades witnessed major advances regarding the elucidation of biosynthetic schemes leading to these fascinating compounds, accounting for the unique substitution patterns of a very vast majority of lichen xanthones. Besides a comprehensive analysis of the structures of xanthones described in lichens, their bioactivities and the emerging analytical strategies used to pinpoint them within lichens are presented here together with physico-chemical properties (including NMR data) as reported since 1996.

Chemical Diversity and Biological Properties of Secondary Metabolites from Sea Hares of Aplysia Genus

The marine environment is an important source of structurally-diverse and biologically-active secondary metabolites. During the last two decades, thousands of compounds were discovered in marine organisms, several of them having inspired the development of new classes of therapeutic agents. Marine mollusks constitute a successful phyla in the discovery of new marine natural products (MNPs). Over a 50-year period from 1963, 116 genera of mollusks contributed innumerous compounds, Aplysia being the most studied genus by MNP chemists. This genus includes 36 valid species and should be distinguished from all mollusks as it yielded numerous new natural products. Aplysia sea hares are herbivorous mollusks, which have been proven to be a rich source of secondary metabolites, mostly of dietary origin. The majority of secondary metabolites isolated from sea hares of the genus Aplysia are halogenated terpenes; however, these animals are also a source of compounds from other chemical classes, such as macrolides, sterols and alkaloids, often exhibiting cytotoxic, antibacterial, antifungal, antiviral and/or antifeedant activities. This review focuses on the diverse structural classes of secondary metabolites found in Aplysia spp., including several compounds with pronounced biological properties.